diff --git a/examples/autoinstall.yaml b/examples/autoinstall.yaml
index bc21a4fb..b35b5c40 100644
--- a/examples/autoinstall.yaml
+++ b/examples/autoinstall.yaml
@@ -3,6 +3,7 @@ early-commands:
   - echo a
   - sleep 1
   - echo a
+locale: en_UK.UTF-8
 refresh-installer:
   update: yes
   channel: edge
diff --git a/scripts/check-yaml-fields.py b/scripts/check-yaml-fields.py
new file mode 100644
index 00000000..db8289b0
--- /dev/null
+++ b/scripts/check-yaml-fields.py
@@ -0,0 +1,20 @@
+#!/usr/bin/python3
+import sys
+
+import yaml
+
+
+config = yaml.safe_load(open(sys.argv[1]))
+
+
+def main():
+
+    for arg in sys.argv[2:]:
+        k, expected = arg.split('=', 1)
+        expected = yaml.safe_load(expected)
+        v = config
+        for part in k.split('.'):
+            v = v[part]
+        assert v == expected, "{!r} != {!r}".format(v, expected)
+
+main()
diff --git a/scripts/runtests.sh b/scripts/runtests.sh
index ef267ce9..a29c13ef 100755
--- a/scripts/runtests.sh
+++ b/scripts/runtests.sh
@@ -26,8 +26,11 @@ TTY=$(tty || true)
 timeout --foreground 60 sh -c "LANG=C.UTF-8 python3 -m subiquity.cmd.tui --autoinstall examples/autoinstall.yaml \
                                --dry-run --machine-config examples/simple.json \
                                --kernel-cmdline 'autoinstall console=\"${TTY#/dev/}\"'"
-python3 scripts/validate-yaml.py .subiquity/subiquity-curtin-install.conf \
+python3 scripts/validate-yaml.py .subiquity/subiquity-curtin-install.conf
+python3 scripts/check-yaml-fields.py .subiquity/subiquity-curtin-install.conf \
         debconf_selections.subiquity='"eek"'
+python3 scripts/check-yaml-fields.py .subiquity/var/lib/cloud/seed/nocloud-net/user-data \
+        locale='"en_UK.UTF-8"'
 grep -q 'finish: subiquity/InstallProgress/postinstall/install_package1: SUCCESS: installing package1' \
      .subiquity/subiquity-debug.log
 grep -q 'finish: subiquity/InstallProgress/postinstall/install_package2: SUCCESS: installing package2' \
diff --git a/scripts/validate-yaml.py b/scripts/validate-yaml.py
index 54b975dc..fb88a6a5 100644
--- a/scripts/validate-yaml.py
+++ b/scripts/validate-yaml.py
@@ -96,12 +96,5 @@ def main():
 
     storage_checker.final_checks()
 
-    for arg in sys.argv[2:]:
-        k, expected = arg.split('=', 1)
-        expected = yaml.safe_load(expected)
-        v = config
-        for part in k.split('.'):
-            v = v[part]
-        assert v == expected, "{!r} != {!r}".format(v, expected)
 
 main()